Pressure responsive switch

ABSTRACT

A pressure operable electrical switch having a diagonally supported flexure beam interposed between a pressure responsive diaphragm and a ball movable against a switch actuator. An exposed adjusting knob permits presetting pressure at which the instrument is to be operative and is located laterally displaced from the ball operatively connected to prevent beam movement at pressures below the setting thereof.

United States Patent [72] inventors Joseph E.Gorgens Trumbull; RandallGoff, Weston, Conn.

211 App]. No. 807,835

[22] Filed Mar. 17,1969

[45] Patented Jan. 19, 19711 [7 3] Assignee Dresser Industries, line.

Dallas, Tex. a corporation of Delaware [54] PRESSURE RESPONSIVE SWITCH10 Claims, 4 Drawing Figs.

200/83 .....l-l01h 35/24 [50] Field of Search 200/83,

[56] References Cited UNITED STATES PATENTS 3,419,693 12/1968 Gould etal.

Primary Examiner-Robert K. Schaefer Assistant Examiner-M. GinsburgAttorneys-Robert W. Mayer, Daniel Rubin, Frank S. Troidl,

Roy L. Van Winkle and William E. Johnson, Jr.

ABSTRACT: A pressure operable electrical switch having a diagonallysupported flexure beam interposed between a pressure responsivediaphragm and a ball movable against a switch actuator. An exposedadjusting knob permits presetting pressure at which the instrument is tobe operative and is located laterally displaced from the balloperatively connected to prevent beam movement at pressures below thesetting thereof.

IPAIENIE UJA M9I9?II $557,329

' INVENTORS JOSEPH anoassns RAQIDALL GOFF rromsv PRESSURE RESPONSIVESWITCH BACKGROUND OF THE INVENTION 1. The field of art to which theinvention pertains includes the art of electricity, circuit makers andbreakers as specifically including the art therein pertaining toswitches operative by fluid pressure or other force and motion producingdevices.

2. Condition responsive switches for various control purposes are wellknown in the industry and available from many sources of manufacture.While commercially available pressure actuated switches are known tofunction well, they are generally characterized by insufficientcompactness, i.e., having too great a height dimension to meetparticular customer needs and/or the inability to be adjustably andconveniently field set to the pressure at which the instrument is to beoperative. Although many switches currently marketed contain one or theother of these features, none by virtue of their particu- Iarconstruction are readily capable of combining both features within asingle instrument in an economic manner enabling the product tofavorably compete in present markets against similar devices having oneor the other of these features.

Typical of the prior art are pressure switches such as those disclosedfor example in U.S. Pat. Nos. 2,249,208; 2,722,580; 2,807,686; and2,919,321. It can be seen from a review of the mechanisms in the devicesof these prior patents, that their relatively sophisticatedconstructions are not amenable to competitively low fabrication cost toprovide a low height, compact pressure switching unit having integralmeans enabling field adjustable presetting of the pressure operatingpoint. t

SUMMARY This invention relates to control instruments and particularlyto pressure responsive electrical switch devices for operating a controlcircuit of external equipment or the like. More specifically, theinvention relates to a pressure responsive control switch characterizedby a highly compact assembly affording a minimum instrument height yethaving the capability of convenient field set adjustability of theinstrument for accurately effecting the set pressure at which the instrument is to be operative. Not only are both of these features readilyand compactlycombined into a single instrument, but this result isachieved with a design affording high vibration resistance, low frictionoperation as to minimize inherent error as otherwise occurs ininstruments of this type. Moreover, the simple construction hereofenables low production cost permitting the instrument to competefavorably in the market place against instruments marketed by otherswithout these combined features.

These results are achieved in accordance with the invention by means ofan assembled arrangement of components that includes a pressuresensitive diaphragm exposed to the pressure to which the instrument isintended to respond. A movable piston is supported in immediate followerengagement centrally aligned against the diaphragm and in turnresponsively moves a ball on which is supported a diagonal flexure beam.Located opposite the beam is a switch actuator in the form of a plungerpin arranged in extended alignment with the ball and operating theswitch to which the circuit leads are connected. The beam acts, via theball, as a second class lever transmitting force to the switch actuator.Concomitantly opposing beam movement against the actuator is a loadingspring acting against the beam axially displaced from the ball forapplying a force at the free end thereof. The spring load is set at thedesired operating pressure at which the instrument is to be responsiveby means of a knurled adjusting knob movable relative to a fixedreference scale of pressure indicia.

Notwithstanding these combined operational features, the switch hereofcan conveniently be constructed within an overall height of about 3inches having a maximum lateral dimension of about 2 36 inches.Accordingly, by means of the invention hereof, features characterizingprior devices of this type are substantially improved on by a novelconstruction not previously known and affording a relatively low costproduct satisfying a long felt need in the industry.

It is therefore an object of the invention to provide a novel pressureresponsive control instrument characterized by a design affordingconvenient preset adjustment of the operating pressure at which theinstrument is to be responsive yet having a higher degree of compactnessthan similar switch mechanisms of the prior art.

It is a further object of the invention to provide a novel pressureresponsive control switch in accordance with the preceding object havinga simplified construction affording relatively low fabrication cost asto enable competitive marketing of this unit against other units withlesser features.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevation view of theswitch instrument hereof partly cut away to expose internal constructiondetail;

FIG. 2 is top plan view of the switch instrument hereof;

FIG. 3 is a sectional elevation taken substantially along the lines 3-3of FIG. 2; and

FIG. 4 is sectional elevation taken substantially along the lines 4-4 ofFIG. 2.

Referring now to the drawings, the illustrated embodiment of theinvention includes a housing 10 representing the lower part of theinstrument and having a shank l l for connection to a system in whichthe instrument is to be employed. For these urposes the shank includes amale thread and a female thread at'2l enabling screw mounting to a well,bracket or other support on which the instrument is to be situated.Upward from the shank the housing enlarges to a hexagonal formation 12on which to externally receive a wrench or the like used to install theinstrument in place and in turn merging into an enlarged and squaredcuplike formation 13 defining an internal recess 15. Supported andsecured via bolts 14, 45 and 50 superposed overlying the cup end of thehousing in pressure tight relation is a top plate 16 being exteriorlycoextensive therewith.

Pressure of a system to which the instrument is to be responsive isreceived within the housing shank via a fluid passage 20 having adefined central axis 25. The passage extends upward to an annularshoulder 27 defining a coaxial bore 22 opening into the housing recess15. Within the recess overlying bore 22 is supported a suitablepreassembled pressure sensitive unit which may be of a type disclosed inGorgens, et al. US. Pat. No. 3,393,6 l 2 incorporated herein byreference. As more fully disclosed in the Gorgens et al. patent, thepressure unit includes a diaphragm 34 attached to the underside of apiston 23, a cylinder 24 circumferentially surrounding the piston and aspring 26 in the form of a symmetrical spidershaped metal elementoverlying the piston to resist movement thereof. Cylinder 24 has anL-shaped cross section, the radially inward directed flange of whichpresents a flat seating surface 28 on which the piston can rest. Forthis purpose piston 23 is of two diameters, the larger being indicatedat 30, and the smaller being indicated at 32. In radial dimension thepiston and cylinder are closely situated but sufficiently spaced topermit axial movement of the former in a relatively friction-freerelation.

On assembly of the unit, a thin piston flange or rim 33 is staked anddeformed over the inner spring ring to secure the spring and piston in afirmly clamped relation while the fluid impervious rubber diaphragm 34is sea-led and clamped at its edges by an O-ring 36. In a manner similarto that described in the Gorgens, et al. patent supra, the piston anddiaphragm are concomitantly urged in a vertical direction in response topressure changes received at the fluid passage 20 being upwardly inresponse to increased pressure and downwardly in response to decreasedpressure.

To transmit piston movement in accordance herewith there is provided aspherical ball 38 freely supported within bore 39 of top plate 16. Theball is normally seated in drilled recessed 40 on the topside of piston23 to be movable conjointly therewith. Bore 39 likewise has an axisextension coincident with axis 25 and is of a diameter providing radialclearance to the ball sufficient to permit frictionless axial movementthereof. 7

Overlying the ball in normally force contact engagement therewith (seeHO. 4) is a flexure beam 44 secured to top plate 16 at one end via bolt45 and relatively free at its opposite end whereat it is formed with acentral bore 46 and an upward-turned flange 47. Received through thebore 46 is a centering bolt 50 extending axially upward parallel anddisplaced from axis 25 to threadedly support an adjusting knob 52 at itsuppermost end. The knob is formed at its underside with a counterbore 53in which to receive a coil spring 54 loaded by compression againstflange 47 as will be explained. In this arrangement the compressiveforce of spring 54 acting against the flexure beam resists upwardmovement of the ball imposed by pressure acting against the underside ofdiaphragm 34.

For these purposes, beam 44 is of a relatively firm inflexible stripmaterial having a window 48 defining a hinge location and is initiallysupported without preloading. The rate of spring 54 is matched to thebeam arm deflection corresponding to scale travelfor pressurecalibrations on scale 68. At zero load, the spring is in its naturaluncompressed state with the beam barely contiguous to the ball withoutany preloading thereon. Likewise, the operating switch differentialbetween on and off," can be governed by appropriate selection of thespring rate. Preferably, a 2 and 3 percent differential is employed forl and amperage service respectively.

Switching operation of the device is conducted by switch unit 57 havinga switch actuator in the form of a vertical plunger or pin 56 downwardlydepending into engagement against the topside surface of beam 44. Pin 56is supported in axial alignment with axis 25, and endures verticalmovement in a follower relation to beam 44. The switch is of a suitabletype commercially available for either line voltage or control linevoltage having terminals 58, 59 and 60 to receive wire leads of thecircuit in which it is to be connected.

Securing the switch in position on top plate 16 is a vertical bracket 62having horizontally extending opposite ends 63 received beneath the nutof each bolt 14. On the opposite face of switch 57 bracket 62 forms anameplate 65 bent into a springlike engagement against the knurledsurface of knob 52. This serves to provide a frictional detent againstthe knob whereby inadvertent resetting of the latter from vibration orthe like is prevented. Along the rightmost edge of the nameplate, asviewed in FIG. 1, is a reference scale 68 of calibrated pressureindicium at which the instrument can be preset to operate. lnaccordance'herewith the indicium are calibrated to coincide with theunder-edge 69 position of knob 52.

To set switch operating pressure knob 52 is hand-rotated by an operatoruntil bottom edge 69 is opposite the desired pressure reading on scale68. Rotating the knob advances it up or down on the threaded shank ofcenter bolt 50 to move underedge 69 relative to pressure indicia onscale 68 corresponding to pressures at which the unit will operate whenthe knob is stayed. Downward movement of the knob increases springcompression against flexure beam 44 thus increasing the force which ball38 must overcome to operate the switch. The converse is also true. lnthis relation therefore, flexure beam 44 forms a second class levertransmitting force to the switch actuator via the ball 38. By means ofcontrol knob 52 being located offset with respect to ball 38 theleverage effect permits using a coil spring 54 having a generally lowerspring rate than would otherwise be required if the latter were locatedin axial alignment between the ball and plunger.

With the arrangement thus described there is disclosed a simplyconstructed, highly compacted, pressure responsive electrical switchingunit. The unit is comprised of a minimum number of operating componentsin which pressure received in the fluid passage 20 acts via the piston23 in a linearly direct axially aligned movement against the switchactuator 56. Ad-

justment can be easily and readily operator set in the field by mereappropriate setting of adjustment knob 52 relative to indicia scale 68.Once the knob has been set to the desired operating point, thedetenteffect of plate 65 prevents inadver- E as disclosed in the Gorgenset al. patent supra will permit any plausible range to be employed. Notonly does the simplicity L of this design have a minimum of operativeand cooperating components which affords economical fabrication but itlikewise contributes to a high degree of compactness having a minimumheight dimension. At the same time, by virtue of the tight-knitcompactness, the unit has a high resistance to vibration which could intime otherwise affect its operating performance. Yet further, the mannerin which the flexurc beam loads the ball against the switch actuatorplunger, eliminates backlash and prevents impact damage which couldotherwise occur. H

By the above description there has been disclosed a novel switching unitresponsive to operating pressure of a system for which it is employed tooperate an appropriate number of control circuits as a function ofpressure change. By the assembly arrangement provided, the switch is ofa highly economical construction affording the combined features ofminimal height and convenient field setting adjustment of theappropriate pressure at which theunit is to be operative.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that allmattercontained in the drawings and specification shall be interpreted asillustrative and not in a limiting sense.

We claim:

1. A pressure responsive device comprising:

a. a housing having a central passage extending from a first end forconnecting to a source of inlet pressure;

b. a pressure yieldable diaphragm secured in pressure tight relation tosaid housing overlying said passage at a location displaced from saidfirst end;

c. movable means having one side operably engaging said diaphragm to bemovable in direct response to yielding thereof and another side having arecess located in direct alignment with the axis of said passage;

d. a ball member seated in the recess of said last-recited 3 means forconjoint movement therewith;

e. control means operative by an actuator movable in axial alignmentwith the axis of said'passage;

f. a pivotal flexure beam secured at one end and relatively free at theother end, said beam extending contiguously between said ball member andactuator and responsive to movement of said ball member to move saidactuator between operative and inoperative position for said controlmeans; and

g. adjustment means to preset the operating pressure of said controlmeans including means to apply a preset biasing force against the freeend of said flexure beam acting in a direction to oppose pressure insaid passage being exerted against said diaphragm.

2. A pressure responsive device according to claim 1 in which saidadjustment means is located axially displaced from said adjustment meansis located axially displaced from said central passage and acts in adirection extending axially parallel thereto.

3. A pressure responsive device according to claim 2 in which saidadjustment means includes a coil spring acting against the free end ofsaid flexure beam and a control knob threadedly mounted to compress thespring against said flexure beam.

4. A pressure responsive device according to claim 3 including pressureunit calibrated indicia means correlated with a reference location onsaid control knob enabling visual observation of the set condition asthe knob is threadedly advanced toward and away from said flexure beam.

5. A pressure responsive device according to claim 4 in which saidcontrol means comprises an electrical switch having contacts forconnecting to a circuit to be controlled. A 6. in a pressure responsivedevice including a housing havmg a central passage extending from afirst end for connecting to a source of inlet pressure, a pressureyieldable diaphragm secured in pressure tight relation to said housingoverlying said passage at a location displaced from said first end; andmovable means having two sides one side of which operably engages saiddiaphragm to be movable in direct response to yielding thereof and theother side of which has a recess located in direct alignment with theaxis of said passage; the improvement comprising;

a. a ball member seated in the recess of said last-recited means forconjoint movement therewith;

b. control means operative by an actuator movable in axial alignmentwith the axis ofsaid passage;

c. a pivotable flexure beam secured at one end and relatively free atthe other end, said beam extending contiguously between said ball memberand actuator and responsive to movement of said ball member to move saidactuator between operative and inoperative positions for said controlmeans; and

d. adjustment means to preset the operating pressure of said controlmeans including means to apply a preset biasing force against the freeend of said flexure beam acting in a direction to oppose pressure insaid passage being exerted against said diaphragm.

7. In the improvement according to claim 6 in which said adjustmentmeans is located axially displaced from said central passage and acts ina direction extending axially parallel thereto.

8. ln the improvement according to claim 7 in which said adjustmentmeans includes a coil spring acting against the free end of said flexurebeam and a control knob threadedly mounted to compress the springagainst said flexure beam.

9. in the improvement according to claim 8 including pressure unitcalibrated indicia means correlated with a reference location on saidcontrol knob enabling visual observation of the set condition as theknob is threadedly advanced toward and away from said flexure beam.

10. In the improvement according to claim 9 in which said control meanscomprises an electrical switch having contacts for connecting to acircuit to be controlled.

mg?" UNITED S'IA'IES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,557,329 Dated January 19, 1971 Inventor(s) Joseph E. Gorgens andRandall Goff It is certified that error appears in the above-identifiedpaten and that said Letters Patent are hereby corrected as sh oxm below:

I Claim 2 line 63 delete "adj ustment means is located axially displacedfrom said" Signed and sealed this 2nd day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Acting Commissioner of Pate:

Attesting Officer

1. A pressure responsive device comprising: a. a housing having acentral passage extending from a first end for connecting to a source ofinlet pressure; b. a pressure yieldable diaphragm secured in pressuretight relation to said housing overlying said passage at a locationdisplaced from said first end; c. movable means having one side operablyengaging said diaphragm to be movable in direct response to yieldingthereof and another side having a recess located in direct alignmentwith the axis of said passage; d. a ball member seated in the recess ofsaid last-recited means for conjoint movement therewith; e. controlmeans operative by an actuator movable in axial alignment with the axisof said passage; f. a pivotal flexure beam secured at one end andrelatively free at the other end, said beam extending contiguouslybetween said ball member and actuator and responsive to movement of saidball member to move said actuator between operative and inoperativeposition for said control means; and g. adjustment means to preset theoperating pressure of said control means including means to apply apreset biasing force against the free end of said flexure beam acting ina direction to oppose pressure in said passage being exerted againstsaid diaphragm.
 2. A pressure responsive device according to claim 1 inwhich said adjustment means is located axially displaced from saidadjustment means is located axially displaced from said central passageand acts in a direction extending axially parallel thereto.
 3. Apressure responsive device according to claim 2 in which said adjustmentmeans includes a coil spring acting against the free end of said flexurebeam and a control knob threadedly mounted to compress the springagainst said flexure beam.
 4. A pressure responsive device according toclaim 3 including pressure unit calibrated indicia means correlated witha reference location on said control knob enabling visual observation ofthe set condition as the knob is threadedly advanced toward and awayfrom said flexure beam.
 5. A pressure responsive device according toclaim 4 in which said control means comprises an electrical switchhaving contacts for connecting to a circuit to be controlled.
 6. In apressure responsive device including a housing having a central passageextending from a first end for connecting to a source of inlet pressure,a pressure yieldable diaphragm secured in pressure tight relation tosaid housing overlying said passage at a location displaced from saidfirst end; and movable means having two sides one side of which operablyengages said diaphragm to be movable in direct response to yieldingthereof and the other side of which has a recess located in directalignment with the axis of said passage; the improvement comprising; a.a ball member seated in the recess of said last-recited means forconjoint movement therewith; b. control means operative by an actuatormovable in axial alignment with the axis of said passage; c. a pivotableflexure beam secured at one end and relatively free at the other end,said beam extending contiguously between said ball member and actuatorand responsive to movement of said ball member to move said actuatorbetween operative and inoperative positions for said control means; andd. adjustment means to preset the operating pressure of said controlmeans including means to apply a preset biasing force against the freeend of said flexure beam acting in a direction to oppose pressure insaid passage being exerted against said diaphragm.
 7. In the improvementaccording to claim 6 in which said adjustment means is located axiallydisplaced from said central passage and acts in a direction extendingaxially parallel thereto.
 8. In the improvement according to claim 7 inwhich said adjustment means includes a coil spring acting against thefree end of said flexure beam and a control knob threadedly mounted tocompress the spring against said flexure beam.
 9. In the improvementaccording to claim 8 including pressure unit calibrated indicia meanscorrelated with a reference location on said control knob enablingvisual observation of the set condition as the knob is threadedlyadvanced toward and away from said flexure beam.
 10. In the improvementaccording to claim 9 in which said control means comprises an electricalswitch having contacts for connecting to a circuit to be controlled.